Over the weekend, The Hustle caught up with Keahi Seymour, inventor of the Bionic Boots, with kind of a bummer story about how his dream of bringing his speed augmenting footwear to the masses had fizzled out since its viral fame a few years ago. It’s an interesting window into the thorny question of when to give up on your dream of turning your passion into a business.

Seymour wowed everyone at Maker Faire Bay Area in 2014 and wrote about building the Bionic Boots for Make: a few months later. The boots use a molded carbon fiber shell and a series of springs to mimic animals like kangaroos that walk on their toes and store energy in their achilles tendons. And they work. They’re a fantastic piece of engineering that really does boost a person’s running speed. Moon shoes, these are not.

But this line in particular stood out:

“I built the Bionic Boots simply because I wanted that experience. Ever since I was 12 years old, I’ve been dreaming of one day dropping into the African savanna and running with cheetahs.”

It’s easy to look at the boots as a failure if you only look at them as a product. Any number of factors could have contributed to the boots not making it to market, including outside companies copying and selling his concept while he was unable to fight back. But if you told that 12-year-old kid that one day he’d be racing at 25mph with his dream boots, he’d be ecstatic.

So while Seymour may be letting go of the dream of the Bionic Boots as a product, he’s certainly not letting go of the boots entirely. As he told The Hustle, “Some people work on old hot rods or bikes. I work on my boots. That’s my passion.”